Size_t for loop questions - making bit crusher with own sensors


I am playing around with some of the example code. The hardware I have are three home made stretch sensors. I’m getting decent values from them and are mapping them to better ranges.

I’m don’t know heaps about programming. Currently I am not getting sound out. I don’t really understand the two for loops in the audio callback. At first I thought the for loop was just used in the example to automate it. But now I get that it’s inside this for loop where I need to put the sound.

I’m currently getting no sound out from channel 1. The sensors are working as they react in the serial monitor. I think that it’s either that I have the output set up wrong. or that the parameters I am setting for bit crush are wrong. Is there somewhere that I can find out the max and min values for the bitDepth and crushRate?

here is my altered bitcrush example code:

#include "DaisyDuino.h"

DaisyHardware hw;

size_t num_channels;

static Oscillator osc, lfo;
static Bitcrush bitcrush;
static Metro metro;

uint8_t depth;

uint8_t string1;
uint8_t string2;
uint8_t string3;

float harpL;
float harpM;
float harpR;

void MyCallback(float **in, float **out, size_t size) {
  float sig;
  Serial.print("string1: ");

  harpL = map(analogRead(string1), 910, 1023, 200, 22000);
  harpM = map(analogRead(string2), 910, 1023, 1, 8);
  harpR = map(analogRead(string3), 710, 1023, 1000, 2000);

  for (size_t i = 0; i < size; i++) {

    sig = osc.Process();

    sig = bitcrush.Process(sig);

    for (size_t chn = 0; chn < num_channels; chn++) {
      out[chn][i] = sig;

void setup() {
  float sample_rate;
  // Initialize for Daisy pod at 48kHz
  hw = DAISY.init(DAISY_SEED, AUDIO_SR_48K);
  num_channels = hw.num_channels;
  sample_rate = DAISY.get_samplerate();

  depth = 1;
  string1 = A6;
  string2 = A5;
  string3 = A4;//r
  pinMode(string1, INPUT);
  pinMode(string2, INPUT);
  pinMode(string3, INPUT); 
  metro.Init(1.0f, sample_rate);

  // Set parameters for oscillator

  // set parameters for bitcrusher

void loop() {}

I’ve checked the output with a different sketch and the sound out is working so it’s not the cable.
Any help or feedback appreciated. Thanks

Documenting in case anyone tries a similar thing. I’m fairly sure that I need to be doing the analogRead inside of the for loop…


You told me on Discord that you’re working on a different code now, so I’ll look at that more recent forum post :slight_smile:

As for where to put the analogRead() function, you can put in the void loop(). Please have a look at the oscillator example and it’ll give you a good idea of how this sort of code is structured.

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Yes! I did switch code. I had this working but I think a bit crusher was the wrong sound to work well with the hardware I’m using.

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